whitesell



Jan. 11, 1955 D. A. WHITESELL 23,923

FOLDABLE'WHEEL DOLLY Original Filed Dec. 14, 1951 2 Sheets-Sheet 1 LLL ll l i I NVENTOR ATTORNEYS United States Patent Ofiice Re. 23,923 Reissued Jan. 11, 1955 FOLDABLE WHEEL DOLLY Denham A. Whitesell, Staunton, Va.

Original No. 2,670,092, dated February 23, 1954, Serial No. 261,729, December 14, 1951. Application for reissue June 24, 1954, Serial No. 439,171

11 Claims. (Cl. 214-330) Matter enclosed in heavy brackets appears in the Original. patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

This invention relates to. dollies for moving vehicle Wheel and tire assemblies, and more particularly to a spring suspended dolly which can receive the shocks incident to moving wheel and tire assemblies onto and off. of the dolly without damage to the dolly.

It is among the objects of the invention to provide an improved tire-moving dolly .and track assembly including. a foldable track and means for releasably locking, the dolly at one end of the track for folding the latter; which includes .a two-part track, the two parts of: which are foldable. together with the dolly included therebetween; whichv includes a spring suspended dolly so that tires can be moved onto and off of the dolly without danger of smashing. or breaking the dolly; which providesguardsv enclosing the dolly rollers so. that tires on. the, .dollly do not interfere. with the operation of the rollers;. which includes a tiltable dolly which can be inclined to receive tire and wheel assemblies from or mount. tire. and wheel assemblies on an inclined vehicle. axle; which will simultaneously receive both tire and. wheel assemblies of ,a. dual wheel arrangement; and which is simple. and durable in construction, economical to. manufacture, easy .touse, and effective and. eflicient in use.

Other objects and. advantages will become apparent from. a- .consideration. of the following. description and appended claims in conjunction with. the accompanying drawings, wherein:

Figure l is a top. plan. view of a track and dolly assembly illustrative. of the invention;

Figure 2vis-a1 side. elevational view of .thetrack and dolly assembly with thetrack. in unfolded condition, as illustrated in Figure. 1.;'

[Figure 3 is a side. elevational view of the track in partlyfoldedwconditiom] Figure; [413 isa longitudinal. cross-sectional view on theline E. 4]l33 ofigure. 1;

Figune'4 isa sectional. view along line 4 4 of Figure 1' on an enlarged scale. showing a: part of the track in broken linein partly folded condition,-

Eigurei isa fragmentary cross-sectional view on an enlarged scale on: the -line..55- .05 Figure [2] 4;

Figune. 6 is: a top. plan: view' of the track and dolly with the track infolded condition;

Figure 7 is a transverse cross-sectional view on the line. 77-- of Figure 6;

Figure 7a.-is, afview similar to-liigmie 7 with the track parts folded down into alignment and with the dolly platformvdepressed:v so thatv its flanges are resting on the tracks" therebeneath as when ovenloaded;

Figure '8. is a longitudinal cross-sectional view on thezline 8-8 of Figure. 6;

Figure. 9.- is- ,a transverse: cross-sectional view on the line 9-9 of Figure 6;

Figure l0:is .an end. elevationalview of the track and dolly assembly. with the track. in v folded condition; looking; atthe right-hand end of the assembly as. illustrated int-Figured;

Figural l: is..-a.side. elevationalview ofv the dolly;

Figure. 12. is. a perspective view of a dolly suspension spring; [and] Figure 13 is a perspective view of a dolly latch lever constituting an operative component of the assembly [.I'fllld Figure: 14 is, a perspective. view on an enlarged scale of'thelefthandhinge plate in Figure I.

With continued reference to the drawings, the dolly assembly includes a track, generally indicated at 10, of elongated, rectangular shape including two parts pivotally connected together in end-to-end relationship for movement relative to each other about an axis extending transversely of the track intermediate the length thereof.

The track part 11 comprises side members 12 and 13 disposed in spaced apart and substantially parallel relationship to each other and end members 14 and 15 connected at their ends to the side members 12 and 13 at the corresponding ends of the latter and disposed substantially perpendicularly thereto.

The side members 12 and 13 and the end member 14 are of right-angular, cross-sectional shape having flat flanges disposed at the bottom side of the track and adapted to rest on a supporting surface, such as a garage or shop floor and having legs upstanding perpendicularly from the flanges, and the end member 15 is a flat bar disposed substantially in the plane of the flanges of the side members 12 and 13 and having triangular projections 16 and 17 disposed one near each end thereof and extending in a direction away from the adjalcent ends of the side members 12 and 13, respective y.

A central reinforcing flat bar 13'; lying substantially in the plane of the flanges of side members 12 and 13, extends parallel to the flanges of the side members 12 and 13 midway thcrebetween with its ends attached to the end members 14 and 15 as by welding.

The track part 18 comprises spaced apart and substantially parallel side members 19 and 20 and an end member 21 extending between and connected at its ends to the side members 19 and 20 at one end of the frame part 18. The side members 19 and 20 and the end member 21 are also of right-angular, cross-sectional shape, each part including a flange portion disposed at the bottom of the track and adapted to rest on a floor or other horizontal support and a leg upstanding substantially perpendicularly from the flange portion. At their ends remote from the cross member 21 the flanges of the side members 19 and 20 are beveled, as illustrated in Figure 1, to lie along the outer sides of the triangular extensions 16 and 17, respectively, and hinge plates 22 and 23 are connected to the side members 19 and 20, respectively, at the outer sides of the upstanding legs of these side members and at the ends thereof remote from the cross member 21.

Hinge plates 24 and 25 are secured to the side members 12 and 13 of the track part 11 at the outer sides of the legs of the side members and at the ends thereof adjacent the end member 15, and these hinge plates 24' and 25 extend beyond the end member 15 and are offset outwardly of the corresponding side members 12 and 13 to overlie the hinge plates 22 and 23 on the side members 19 and 20.

In Figure 14 hinge plate 25 is shown formed with offset bifurcated portions ZIP-25 having a horizontal slot therebetween.

A pivot bolt 26 extends through registering apertures in the hinge plates 22 and 24, and a complementary pivot bolt 27 extends through registering apertures in the hinge plates 23 and 25, these bolts serving as hinge pins pivotally' connecting the track part 18 to the track part 11 for folding movement of the two track parts relative to each other about an axis extending transversely of the track.

The ends of the upstanding legs of the side members 19 and 20 are preferably extended upwardly in semicircular form, as indicated at 28 and 29, and apertured to receive the bolts 26 and 27 to reinforce the pivotal connection between the two frame parts. The beveled ends of the flange portions of the side members 19 and 20, together with the outer sides of the triangular extensions 16 and 17, provide break lines extending diagonally of the side member flanges at the location of the pivotal connection between the two parts of the frame, so that dolly Wheels may roll over these break lines without encountering any substantial unevenness in the flange portions of the track.

A U-shaped handle 30 is connected at its ends to the end member 21 near the opposite ends of the latter and extends outwardly from this and member to provide convenient means for manually raising and lowering the outer end of the track part 18. Apertured lugs 31 and 32 also project outwardly from the end member 21 one near each end thereof, and a latch rod 33 is journaled in these lugs and provided at its ends with hook formations 34 and 35 which engage in apertures 36 and 37 provided in the upstanding leg of the end member 14 when the two parts of the track are folded together to releasably latch the two parts of the track in folded condition, as is particularly illustrated in Figure 9.

A torsion spring 38 surrounds the latch rod 33 adjacent the lug [38] 32 and is connected at one end to this lug and at its other end to the latch bar and acts to resiliently urge the hook formations 34 and 35 inwardly of the apertures or recesses 36 and 37 when the track parts are folded together and a handle 39 is provided on the latch rod for manually moving the hook formations out of the corresponding recesses.

Rectangular plates 40 and 41 are secured each along one edge thereof to the upstanding leg of the track side member 19 at spaced ,apart locations along this side member, and are inclined outwardly and downwardly from the top edge of the upstanding leg of the side member. Similar plates 42 and 43 are secured each along one edge to the upstanding leg of the track side member 21) at the upper edge of this leg and at locations spaced apart longitudinally thereof and are inclined outwardly and downwardly from the top edge of the upstanding leg of this track side member. These plates 4% 41, 42 and 43 constitute ramps to facilitate rolling pneumatic tires over the upstanding legs of the track side members 19 and 29 when the tires are moved onto or moved off of the associated dolly.

The dolly, generally indicated at 45, comprises a plate 46 of rectangular shape having a width substantially equal to the distance between the upstanding legs of the track side members. [and] The length of the dolly 45 may be approximately one-half the length of the track 10. Referring to Figures 1, 3, and 6, the dolly 45 may extend from where its left hand end is adjacent end 14 of tank part 11 to where its right hand end may terminate in alignment with the right hand end of hinge plates 22 and 23. However, the dolly is shown as having a length somewhat less than one-half the length of the track and provided with transversely extending ribs 47 and 48 of channelshaped cross-section extending transversely thereof one near one end and one near the mid-length location thereof, and projecting upwardly from the normally upper surface of the plate. The ridges 47 and 48 are reinforced by inclined gussets, as indicated at 49 and extending from the upper edges of the ribs 47 and 48 to the upper surface of the plate 46 at locations spaced from the adjacent lower edges of the ribs.

The plate 46 has flanges 51 and 52 extending perpendicularly one from each longitudinal edge thereof sub stantially perpendicular to the plate and in a direction away from the ribs 47 and 48, so that these flanges depend from the platform portion of the plate when the dolly is in operative, upright position, as illustrated in Figures [4] 3 and ll. These flanges give longitudinal rigidity to the plate, while the ribs 47 and 48 provide transverse rigidity, and the edges of the flanges remote from the plate are inclined toward the plate from a location between the rib 48 and the end of the plate remote from the rib 47 to the end of the plate remote from the rib 47, so that the platform of the dolly can be tilted by raising the end of the dolly adjacent the rib 47. The flanges 51 and 52 extend vertically and in spaced relation above the flanges of track side members 12 and 13 and rest thereon when the dolly 45 is overloaded as shown in Figure 7a.

An axle 53 extends transversely of the dolly platform below the rib 47 and a similar axle 54 extends transversely of the platform below the rib 48. A bowed, flat spring 55 is disposed in the rib 47 with its center portion convexly opposed to the under side of the web of the channelshaped rib, and is provided in its end with notches 56 and 57 in which the axle 53 is received near the respectively opposite ends of the axle. The spring is also provided with apertures 58 and 59 disposed near the inner ends of the notches 56 and 57, respectively, and elongated longitudinally of the spring. Bolts 60 and 61 extend through apertures in the web portion of the rib 47 one near each end of the rib and through the apertures 53 and 59 in the spring 55 to secure the spring in the rib.

A spring 62, similar to the spring 55 but preferably somewhat wider and stiffer than the spring 55, is disposed in the rib 48 and provided at its ends with notches receiving the axle 54 and near the notches with elongated apertures receiving bolts, as indicated at 63 and 64 which extend through apertures in the web portion of the rib 4S and through the elongated apertures in the spring 62 to secure the spring in the rib.

Thus, when a load is received on the platform 48, springs and 62 will flex, as shown in Figure 7a, and move with respect to their securing bolts, -61 for spring 55, and 6364 for spring 62. S0 also the slotted ends of the springs will move along the axles 53 and 54 extending therethrough. Should the load be excessive for the springs 55 and 62, the platform 46 is depressed so that its longitudinal side flanges 51 and 52 contact the tracks therebelow and the load is transferred to the tracks without damage to the dolly.

Rollers 67 and 68, preferably in the form of sealed roller bearings, are mounted on the axle 53, one at each end of the axle and corresponding rollers 70 and 71 are mounted on the axle 54, one at each end thereof, and are adapted to run on the flange portions of the side members of the track.

Stub axles [71] 73 and 72 are secured on the plate 46 adjacent the end of the plate remote from the rib formation 47 and project laterally from the plate one at each side of the latter. Rollers 74 and 75 are mounted on the stub axles 72 and 73, respectively, and are disposed at the opposite sides of the platform plate 46 of the dolly, these last mentioned rollers being smaller than the rollers 67, 68, 70 and 71, to provide for tilting of the dolly, as mentioned above.

Fenders 77 and 78 of substantially semicylindrical shape are mounted on the platform plate 46 and receive the upper portions of the rollers 67 and 68, respectively, to guard the portions of these rollers extending above the platform plate against contact with tires supported on the platform. Similar fenders 79 and 80 are mounted on the platform plate and cover the upper portions of the rollers 70 and 71, while fenders 81 and 82 of substantially the same shape but smaller than the above-described rollers, are mounted on the platform plate and receive the upper portions of the rollers 74 and 75, respectively.

With the above-described arrangement, when it is desired to remove heavy pneumatic tires from a vehicle such as a truck or bus, the end of the associated axle adjacent the tire or tires to be removed is raised by a jack until the tires are lifted a sufficient distance above the floor to permit the end member 14 of the track to pass under the tires. The track in unfolded condition is then slid along the floor until the part 11 of the track is under the tire or tires to be removed, and the dolly is moved onto this part of the track and disposed under the tire or tires. The tire-carrying wheels will now be released from the associated axle, and, if necessary, the corresponding end of the axle slightly lowered to free the wheels from the axle with the tire supported on the dolly. The dolly will now tilt to a position in which it is substantially parallel to the axle one end of which has been raised by the jack. With the wheels free of the axle, the dolly is moved back from the track portion 11 onto the track portion 18, and

the tires may now be rolled off of the dolly and down the ramps 40 and 41 or 42 and 43 to the floor.

When the tires and wheels are replaced on the axle, with the dolly in the part 18 of the track, the tires and wheels are rolled up selected ramp plates onto the dolly, and the dolly is then moved onto the part 11 of the track, tilting as necessary, to align the wheel hubs with the end of the corresponding axle, and slide the Wheels onto the axle, the inclination of the dolly particularly facilitating the sliding of the brake drum carried by the wheel or by the inner wheel of a dual wheel set, over the brake shoes mounted on the axle.

When the dolly is not in use, the track is preferably folded into the compact condition illustrated in Figures 6 [to 10, inclusive?], 7, 810, inclusive, for convenient storage. In order to accomplish this, the dolly 45 is positioned on the track 11 and the handle 30 is manually raised, bringing the track part 18 first to the upright position illustrated in Figure [3] 4.

When the dolly is not in use, the track is preferably folded into the compact condition illustrated in Figures 6 to 10, inclusive, for convenient storage. accomplish this, the dolly 45 is positioned on the track part 11 and the handle 30 is manually raised, bringing In order to sagas the-.atmckzpatt r18 firststo th empright position illustrated intEigureeS.

:lug:oradetentsBSunmounted;mntathessiderflange552 of the:dolly:=.adjaeentttne zupstanuingrleg ofathetsideimember 13of t-h tframe;andtthetnpstandingulegpflthe si'demembcrtil linstprovidedt with-.an aperture-adjacent. the: .detent 85. A lug8l-aprojectstoutwardlyfrom the outer side'of the;upstandinguleg-ofv thezframel side member. 13 iata locatiom spaced-fromthe;- apertureSG; and carries-an upwardly extendingvbolt-or rivet 188.. (A latch.leverr89 hasuatcone endianeenlarged formation 90 provided-with1antelongated aperturellrreceivingzthepin 88uand with anaperture 92 spaced: from; the aperture 9.1. .At. its, other. endthe. lever 89. ispprovided =with.-=ai hookiformation, 93 .which, projects thrtulgh1 the .aperture .86, inwthe upstanding leg: ofv the frame sidemember 13.

"Asguide, plum-94". is. mounted: on .the outer. side. of the Equpstandingsleg of..the..frame.side, member .13 between elaperture. 8min theI-leg. and the: hinge. plate .25. and provides,a. .bore l.95..extendin g. longitudinally oftthetupstanding leg .cfsthefframe. side. members 1132],, bifurcations 25 .-25

andforms aside. couerifottslot '95. and. dbore. 95. isthereby formed. ,-A.ro'd. 9'6v.extends through the bore 95 and has at one end an offisetiformation. received in the aperture 9Zin'the latch. lever93. A'plunger97is mounted on the other end of the rod"96'andbears atits 'distal end against the adjacent edge 100 of the hinge plate 23, and a compression spring- 98 surrounds the rod within'the bore 95 between the inner-or proximalen'd-of the plunger 97 and an abutment 99 .at the .endofthebore 95 adjacent the aperture "86. [The hinge plate 23 has its corner adjacent thenpivotbolt .100,rounded-;olf on annarcuate curve .centeredcnthe. axistof the bolt.-27,]

fiWithithism-arrangement, when the frame part18'has been broughntoflthe uprightjposition illustratedin Figure [3] 4, the wedge of the hingeplate -23wengagedbythe plungergIZ'IJ 97 will have been movedawaytromrthe plungensothat the spring 98 willtmoveizthe rod 96:in=a direction to.;,project the hook formation :93 of the latch lever 89 through the aperture 86 .andinto engagement with the detent85 on the adjacent "side; flange of the dolly to lock the .i'dolly in'the portion 11 .of the frame. The hook 93fhaswa cut out portion"93 in" its 'edge which seats ogainsfthe adjacent edge of aperture "86" in side member 137due to the movemenr-of-the-latch lever 89permitted by its-"elongated slot -91 --therein. "The frame part '18 is then swung over until it is superimposed on the frame part 11, as illustrated in Figures 9 and 10, and the hook formations 34 and 35 of the latch rod 33 are engaged in the apertures 36 and 37 to latch the two parts of the frame in folded condition with the dolly 45 included therebetween.

When the dolly is again unfolded for use, the latch plate 23 moves the plunger 97 in a direction to pull the hook formation 93 of the latch lever 89 outwardly of the aperture 86 and away from the detent 85 to release the dolly for movement longitudinally of the frame when the latter is in unfolded condition.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are, therefore, intended to be embraced therein.

What is claimed is:

l. A vehicle tire dolly comprising a track of elongated rectangular shape including two parts of substantially equal length pivotally connected together in end-to-end relationship for movement relative to each other about an axis extending transversely of said track, a dolly having a length somewhat less than one-half the length of said track mounted on the latter for movement from one end to the other end thereof, the two parts of said track being foldable together with said dolly disposed therebetween, and latch means carried by one of said track parts and engageable With said dolly as said track parts are folded together to hold said dolly on said one track part while said track parts are being folded, said latch means being released to free said dolly upon unfolding of said track parts.

2. A vehicle tire-moving dolly assembly comprising a track of elongated rectangular shape and a dolly adapted B towrurron said'trackaan/d inclndingaa'platformrof=rectangular 'shape havingtribswofzchannelashapedcrossssectionzrextending transversely thereof adjacent lone send .L and ;the amidlength location:of:said.zplatformvandfflangeszextending one along &each wlongitlldinal sedge :rOf said platform, taxles extending: transversely;ofrzsaidaplatform. one. adjacentit'the openrside.ofieachzofssaid ribs, rollers. mounted'sonerona each end of. each axle, sprin-gsadisposed zone-tin. each of" saidcri'bs and ==engaging sthe :corresponding iiaxles 1 supporting .said platform tonssaidxrollers, rollers smaller than c the abovementioned rollers. mountedwon usaidaplatformsone. at coach side and atrthe. other tend;thereof 'forssupporting saidzplatform in a tilted.position,-andtfenderstmountedon. said platform zand respectively nreceiving tthe portions. of said rollers extending abovesaidplatform.

.3. .A' vehicle tirewzdolly. comprisingaairacktincluding two parts of substantially equal lengthpivotally. connected together in end-'tor'en'd relationship-fori movement relative to cach otheraboufian: :axis extending transverselymof; said track, a dolly. having :a length. approximately one-halfxthe length of .said track; m'ountedt onvthe. latterv for' movement from one end -.-tot theotherrend; thereof, the 'two parts of said track being folda-blef together: with said dolly. disposed therebctween and laich meansscarriedrby one of said truck parts, andrengageable with. said daily as .said 2 track parts are folded :zogethereto 'hold-saidudollyon said oneitrack part 'tw-hile'said rtrack :parts are abeing folded, said :latch means; beingrreleasedato free saidrdolly upon. unfolding of saidtrackparts.

.4. Arvehiclettire removingdollyt'assembly comprisingra track of elongatedrectangularnshape and a dollyadapted tovru-n-zon said: tracks-and including a. platform of rectangular "shape having ribs 00] achannel-shaped CTOSSaSECtiOJl extendingtransversely thereof .zadjucent 'one end and the mid-lengthslocation:ofvsaidcplutform, and-flanges extending one/"along.:eachKlongitudinal edgeofvsaid platform, axles extending.=transversely of. 1 said. platform; one adjacent the open side of each of said ribs, rollers mounted one on each endrofa-each axle, springsadisposedone. in each. of said ribs and: engaging the,correspondingaxles supporting said "platform-.on said rollers.

.5 ..-A vehicletire dolly-comprising a'track ofwelongated rectangular shape/including two parts of substantially equal length :pivotally connected together in endvto-zend relationship for movem-cntrelativeio each otheraboutian axis extending transversely of said track, a dolly mounted on the track for movement from one end to the other end thereof and adapted to be housed between the two track parts when folded together about said axis, one of said track parts having a laterally extending portion attached thereto, and latch means connecting said dolly and said laterally extending portion to hold said dolly on said one track port.

6. A vehicle tire dolly comprising a track of elongated rectangular shape including two parts of substantially equal length pivotally connected together in end-to-end relationship for movement relative to each other about an axis extending transversely of said track, and a dolly mounted on the track for movement from one end to the other end thereof, and adapted to be housed between the two tracks when folded together about said axis, said dolly having a platform, transversely extending axles, rollers mounted one on each'oxle to roll on said track, and spring means yieldable on overload of said dolly to transgifl the overload to said track without damage to said 7. A vehicle tire dolly comprising a track of elongated rectangular shape including two parts of substantially equal length pivotally connected together in end-to-end relationship for movement relative to each other about an axis extending transversely of said track, and a dolly mounted on the track for movement from one end to the other thereof, and adapted to be housed between the two tracks when folded together about said axis, said dolly having a platform including longitudinal depending skirt portions along each side that extend downward to where their lower edge is in close spaced relation to said track. and spring means associated with said platform and axles whereby on overload of said dolly, the spring means yield to permit the lower edges of said skirts to rest on said track so that the load on the dolly is transmitted to said track without damage to said dolly.

8. A vehicle tire dolly comprising a track of elongated rectangular shape including two parts of substantially equal length pivotally connected together in end-to-end relationship for movement relative to each other about an axis extending transversely of said track, a dolly mounted on the track for movement from one end to the other end thereof and adapted to be housed between the two tracks when folded together about said axis, one of said track parts having a laterally extending portion attached thereto, and latch means connecting said dolly and said laterally extending portion to hold said dolly in between the two track parts when folded together, said dolly including a tire'supporting platform having portions thereof in close spaced relation above said track, transversely extending axles, rollers mounted on the axles and adapted to roll along said track, and spring means yieldable on an overload on said platform causing said portions of the platform in close spaced relation above the tract to contact the track thereby transmitting the overload to the track without damaging said dolly.

9. A vehicle tire-moving dolly comprising a track of elongated rectangular shape including two parts pivotally connected together in end-to-end relationship for movement relative to each other about an axis extending transversely of said track, and a dolly having supporting rollers thereon for rolling engagement with said track from one end to the other end thereof and adapted to be housed between the two track parts when folded together about said axis, said track parts comprising spaced apart and substantially parallel side members of right-angular crosssectional shape, including inwardly directed flanges adapted to rest on a substantially horizontal supporting surface and legs upstanding perpendicularly from said flanges along the outer edges of the latter, and a single end member for each track part connected between said side members at the outer ends thereof, said inwardly directed flanges of each track part that are in alignment having their ends in abutting end-to-end engagement and said abutting ends of the flanges extending at an acute anglke to the longitudinal direction of said flanges of each trac 10. A vehicle tire-moving dolly for rolling engagement on a flat supporting surface comprising, in combination, a platform of rectangular shape having a plurality of spaced apart ribs of channel-shaped cross-section extending transversely thereof and flanges extending one along each longitudinal edge of said platform, axles extending transversely of said platform one adjacent the open side of each of said ribs, rollers mounted one on each end of each axle, springs disposed one in each of said ribs and engaging the corresponding axles supporting said platform on said rollers thereby permitting said platform, upon overloading to move downwardly uniformly at opposite edges thereof and causing said flanges extending along the longitudinal edges to engage said supporting surface.

11. A vehicle tire-moving dolly for rolling engagement on a flat supporting surface comprising, in combination, a platform having spaced side and end edges and having a plurality of spaced apart recessed ribs extending transversely thereof, and having open sides in the lowermost face of said platform, and a plurality of rigid depending platform support members secured to said platform adjacent oppositely and spaced edges thereof, and extending below the lowermost face of said platform, axles extending transversely of said platform, each of said axles being adjacent the open side of one of said ribs, rollers mounted one on each end of each axle, resilient means disposed in each of said ribs and interconnecting said platform and said axles supporting said platform on said rollers, thereby permitting said platform, upon overloading, to move downwardly uniformly at opposite edges thereof and causing said rigid platform support members secured to said platform to engage said supporting surface.

References Cited in the file of this patent or the original patent UNITED STATES PATENTS 652,648 Summer June 26, 1900 1,370,732 Corbett Mar. 8, 1921 1,415,857 Avery May 16, 1922 1,535,762 Brejska Apr. 28, 1925 1,620,323 Bugatti Mar. 8, 1927 1,776,262 Noir Sept. 23, 1930 1,911,240 Rosenthal May 30, 1933 2,246,628 Heckman June 24, 1941 2,456,218 Semisch Dec. 14, 1948 2,484,951 Kubo Oct. 18, 1949 2,503,138 Smith Apr. 4, 1950 2,539,274 Sagen Ian. 23, 1951 2,563,927 Engle Aug. 14, 1951 2,594,270 Niederhauser Apr. 22, 1952 

